An Algerian who was branded a terror suspect after being acquitted in the ricin plot trial, was yesterday cleared of being a threat to Britain's national security. Mr Justice Mitting, chairing the special immigration appeals commission (Siac), ruled that there were no national security grounds to deport Mouloud Sihali back to Algeria as there was no "evidence or intelligence that he has ever been a principled Islamist extremist".

An Old Bailey jury cleared Mr Sihali, 30, of taking part in an alleged terrorist conspiracy to spread the poison ricin in London. But at the end of the case he was re-arrested and has lived under virtual house arrest since.

"This has been 19 months out of my life. I was labelled a threat to national security which I am not. Who will give me my 19 months back?" Mr Sihali asked after his Siac hearing yesterday.

Restrictions against him, including electronic tagging, will be relaxed, but the Siac judges dismissed appeals against deportation from three other Algerian terror suspects, including another cleared ricin trial defendant known only as W. The judges ruled that diplomatic assurances from the Algerian government were sufficient to ensure their safety, an assessment which could clear the way for their removal from the UK.

Mr Sihali came to Britain in 1997 claiming he had fled Algeria to avoid compulsory military service. He lived for several months at the notorious Finsbury Park mosque in north London.

At the time of the ricin trial he admitted two counts of possessing false passports and received 15 months imprisonment in Belmarsh maximum security prison. But he was cleared of charges connecting him with the ricin plot and was released soon after, as he had already served the time on remand.

The Siac judges ruled yesterday that he had used false names and documents, fraudulently opened several bank and credit card accounts and falsely claimed state benefits and lied about them at the Old Bailey trial. But they added there was nothing in the evidence to suggest he knew that those he helped were terrorists.

The judges said they were satisfied that although he was unprincipled, he did not engage in anything beyond petty dishonesty. "Whatever the risk to national security he may have posed in 2002, the risk now is insignificant," they concluded.

Mr Sihali may yet face deportation on immigration grounds. The home secretary has 10 days to appeal.

Mr Sihali's lawyer, Natalia Garcia, said he had had to endure years of imprisonment in Belmarsh and control order-style restrictions on the basis of faulty intelligence and political spin. "Having cleared his name once in front of a jury ... he had to face the sheer injustice of the same evidence being used against him by the government to try to deport him as a risk to national security ... the government finally admitted that Mr Sihali is not a terrorist or even a fanatic."

She said the deportation proceedings had been brought to "save face" after the ricin plot acquittals, a plot that she claimed had been used to justify the invasion of Iraq.

The Home Office minister, Tony McNulty, said he was disappointed with the Siac ruling and would examine the prospects of overturning it. He welcomed the court's approval for the deportation of the other three Algerians, who cannot be named for legal reasons, saying the court had again upheld the view that it was safe to send terror suspects back to Algeria.